/*
 *  SableJBDD, a Java Binary Decision Diagram package.
 *  Copyright (C) 2003  Feng Qian
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License as published by the Free Software Foundation; either
 *  version 2.1 of the License, or (at your option) any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
//$Id: SoftBddCache.java,v 1.1 2004/03/12 00:16:02 fqian Exp $

package SableJBDD.bdd.internal;

import SableJBDD.bdd.JBddNode;
import SableJBDD.cache.TripleIntKeyCache;
import java.lang.ref.SoftReference;

/**
 * A soft triple key cache uses soft references for cached objects. It does
 * not prevents cached objects from being garbage collected.
 *
 * @author Feng Qian
 */
public class SoftBddCache extends AbstractBddCache {

  /**
   * Defines a soft cache with a specific cache implementation.
   */
  public SoftBddCache(TripleIntKeyCache impl) {
    super.cacheImpl = impl;
  }

  protected Object makeCacheValue(JBddNode node) {
    return new SoftReference(node);
  }

  protected JBddNode getNodeOutOfCacheValue(Object cvalue) {
    return (JBddNode)((SoftReference)cvalue).get();
  }
}
